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Radon Levels in Clay County, Nebraska

EPA puts Clay County in Zone 1, its highest radon zone, and only 27 radon tests from it are on file with CDC (2023). Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    26.6%

    8.3 pts below NE

    Clay
    26.6%
    Nebraska
    34.9%

    282 tests, 2021

  • Median result

    0.9pCi/L

    Below action level

    Clay
    0.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2021

  • Tests reported

    282

    22nd of 59 by tests

    Clay
    282
    Douglas
    10,416

    Reported to CDC before any fix, 2021

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Nebraska

    54 of 59

    Lowest quarter

    Clay
    26.6%
    Burt
    74.5%

    By share, of 59 with 30+ tests

Read a result for Clay County

Starts at Clay County's median, 0.9 pCi/L

0.9pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 0.9 pCi/L

Below 2 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is below 2 pCi/L, the level at which EPA says a fix should be considered. Clay County's median reported result, 2021.

Interpret this reading

The data

Clay County, At a glance

Clay County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Clay County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Clay County, 2023

Share of reported tests at or above 4 pCi/L, by year, Clay County
Share of reported tests at or above 4 pCi/L, by year, Clay County
YearShare of reported tests at or above 4 pCi/L
201481.6%
201574.1%
201679.6%
201773.3%
201867.2%
201972.9%
202077.8%
202126.6%
202284.0%
202366.7%

2023: 66.7%. Across these years the share ran from 26.6% to 84.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

Only 27 tests were reported to CDC for Clay County over 2023, and tests are often run on homes being sold or already suspected of a problem: so few describe neither the county nor this house.

Measured: CDC tracking data. Figure above: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Clay County, Compared

Clay County radon figures, compared

Calculated by Radon411

Clay County's 282 reported tests in 2021 had a middle value of 0.9 pCi/L and a maximum of 25.1 pCi/L, and 26.6% reached 4 pCi/L. Nebraska as a whole (83 Nebraska counties, pooled) comes to 34.9%: 8.3 points higher than here.

The newest figure, in 2023, counts only 27 tests (66.7% at or above 4 pCi/L), too few to compare, so this reading uses the 282-test figure.

Among its state's counties it ranks 54th of 59 Nebraska counties with 30 or more tests for the same period. Statewide for the same period, Burt County reported the highest share (74.5%) and Howard County the lowest (11.1%).

Below the action level, 192 tests (68.1%) came in under 2 pCi/L, against 40.4% statewide, and 15 tests (5.3%) fell between 2 and 4, against 24.7% statewide. The busiest year on file was 2021, with 282 tests reported; the quietest, 2022, had 25.

EPA's 1993 zone map puts Clay County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 100% of the county's land high radon potential.

Next door, the shares run from 42.6% in Adams County to 67.5% in York County. Over 8 years of annual figures the share fell 55.0 points, from 81.6% in 2014 to 26.6% in 2021; its peak was 81.6% in 2014.

Share of reported tests at or above 4 pCi/L by year, Clay County against Nebraska2014 to 2021, years with 30 or more tests: Clay County 81.6% to 26.6%, the state's pooled share 34.9% in 2021.
Clay CountyNebraska, pooled
Share of reported tests at or above 4 pCi/L by year, Clay County against Nebraska: data table
YearTestsClay County, at or above 4 pCi/LNebraska, pooled
201411481.6%50.5%
201517474.1%53.3%
201614779.6%47.4%
201713573.3%47.7%
201817467.2%44.5%
201917772.9%44.3%
202010877.8%42.2%
202128226.6%34.9%
Clay County against Nebraska, the United States and nearby counties, 2021
AreaTestsAt or above 4 pCi/LMedianDifference from Clay County
Clay County28226.6%0.9 pCi/LThis county
Nebraska, pooled83 counties, pooled38,37034.9%Not pooled+8.3 points
United States, pooled807 counties, pooled344,60424.4%Not pooled−2.2 points
Burt Countyhighest in the state14174.5%9.6 pCi/L+47.9 points
Howard Countylowest in the state5411.1%2.0 pCi/L−15.5 points
Webster County, NEborders it1580.0%4.1 pCi/L+53.4 points
York County, NEborders it24967.5%5.7 pCi/L+40.9 points
Nuckolls County, NEborders it6060.0%5.3 pCi/L+33.4 points
Hamilton County, NEborders it26456.8%4.4 pCi/L+30.2 points
Fillmore County, NEborders it18043.3%3.7 pCi/L+16.7 points
Adams County, NEborders it40842.6%3.4 pCi/L+16.0 points
Where Clay County's reported results fell, 2021, beside Nebraska and the United States
ResultClay County testsClay County shareNebraska shareU.S. shareAgainst Nebraska
Under 2 pCi/L19268.1%40.4%54.4%+27.7 points
2 to 4 pCi/L155.3%24.7%21.2%−19.4 points
4 pCi/L and above7526.6%34.9%24.4%−8.3 points
Clay County ranked among the 59 Nebraska counties with 30 or more tests, by share at or above 4 pCi/L, 2021
CountyRankTestsAt or above 4 pCi/LMedian
Dawson County49 of 5914131.9%2.7 pCi/L
Knox County50 of 5936631.1%2.8 pCi/L
Sarpy County51 of 593,72629.5%2.2 pCi/L
Lancaster County52 of 5910,35328.2%2.0 pCi/L
Platte County53 of 5951328.1%2.6 pCi/L
Clay County54 of 5928226.6%0.9 pCi/L
Chase County55 of 593625.0%3.1 pCi/L
Hall County56 of 5972621.9%2.5 pCi/L
Lincoln County57 of 5932117.8%2.1 pCi/L
Dakota County58 of 5988511.9%0.7 pCi/L
Howard County59 of 595411.1%2.0 pCi/L
Clay County radon tests by year, against Nebraska's pooled share
YearTestsAt or above 4 pCi/LMedianHighestNebraska, pooledChange from the row before
20232766.7%5.7 pCi/L16.0 pCi/L38.2%−17.3 points
20222584.0%9.8 pCi/L29.8 pCi/L34.0%+57.4 points
202128226.6%0.9 pCi/L25.1 pCi/L34.9%−51.2 points
202010877.8%7.7 pCi/L21.4 pCi/L42.2%+4.9 points
201917772.9%8.7 pCi/L25.9 pCi/L44.3%+5.7 points
201817467.2%5.5 pCi/L23.5 pCi/L44.5%−6.1 points
201713573.3%5.2 pCi/L19.2 pCi/L47.7%−6.3 points
201614779.6%7.9 pCi/L17.3 pCi/L47.4%+5.5 points
201517474.1%6.8 pCi/L16.3 pCi/L53.3%−7.5 points
201411481.6%8.6 pCi/L17.9 pCi/L50.5%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Clay County, Geology

The ground under Clay County

Predicted

USGS's geologic map puts all of Clay County's mapped land in one class: high radon potential. All of it lies in the area the map calls Pre-Wisconsin glacial deposits, to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under Clay County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Pre-Wisconsin glacial depositsLoess-mantled glacial drift.High13100%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Clay County beside the ground around it

Clay County has more high-potential ground than Nebraska as a whole: 100% of its land against 40.9%. Of the 6 counties that border it, none has as large a share of high-potential ground; Fillmore County comes nearest at 100%.

Share of land by USGS radon potential: Clay County, the 6 counties bordering it and Nebraska
AreaEPA zoneLow potentialModerate potentialHigh potential
Clay CountyZone 1NoneNone100%
Adams CountyZone 1None0.1%99.9%
Fillmore CountyZone 1NoneNone100%
Nuckolls CountyZone 1NoneNone100%
Hamilton CountyZone 1None12.6%87.4%
Webster CountyZone 1NoneNone100%
York CountyZone 1NoneNone100%
Nebraska93 counties, pooled by land areaVaries28.2%30.9%40.9%

The map rates the ground, not the air in any home.

Local help

Clay County, Local resources

Radon testing and mitigation in Clay County

What Nebraska's program says
Phone
(402) 471-1005
Licensing of radon professionals
If radon testing is done in schools, offices, or other places of work, it must be done by a licensed radon measurement business.

What it means

Clay County, Questions

Questions about radon in Clay County

Are radon levels high in Clay County?

In 2023, 66.7% of the radon tests reported to CDC for Clay County, Nebraska were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.7 pCi/L. Of 59 Nebraska counties with 30 or more tests for the same period, 53 reported a higher share; pooled, the state comes to 34.9%.

Which counties border Clay County?

Clay County borders 6 counties: Adams County, Fillmore County, Nuckolls County, Hamilton County, Webster County and York County.

Products

Clay County, Products

Testing a home in Clay County

In Clay County, 26.6% of 282 tests reported to CDC in 2021 reached 4 pCi/L, against 34.9% pooled across Nebraska. In Zone 1 the year-round level in Clay County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Clay County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Clay County

Explore

Clay County, Bordering counties

Counties bordering Clay County

Calculated by Radon411

Clay County, Cities and towns

Cities and towns in Clay County

The Census Bureau estimates 6,170 residents in Clay County for July 1, 2025, 69 more than in 2020 (+1.1%). That works out to 11 people per square mile of land. Its largest town, Sutton, has 1,466 residents, 23.8% of the total. Testing is reported here more often than across the state: CDC's 282 reported tests for 2021 come to 45.7 for every 1,000 residents (2025 estimate), against 19.0 for Nebraska.

From Sutton to Saronville, CDC publishes no figure by town: each reads Clay County's.

The cities and towns in Clay County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sutton1,466+1.2%23.8%
Harvard952+0.6%15.4%
Clay Center730+1.1%11.8%
Edgar431+1.2%7.0%
Fairfield337+1.5%5.5%
Glenvil269+1.1%4.4%
Trumbullextends beyond Clay County200+1.5%Counted whole
Ong49Level0.8%
Deweese43Level0.7%
Saronville37Level0.6%

10 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025). A place that extends beyond Clay County is counted whole, so it has no share.

Clay County, Homes

Homes in Clay County

Clay County is a place of houses on their own lots: 87% of its 2,816 homes are detached single-family houses, against 72% across Nebraska. The homes are older than Nebraska's as a whole: half were built before 1957 (1975 for Nebraska), and 52% date from before 1960. Owners live in 81% of the occupied homes (Nebraska: 67%), so for most households a test and a fix are their own to order.

Homes in Clay County, Nebraska, 2019 to 2023
HomesClay CountyNebraska
Housing units2,816855,631
Detached houses87%72%
In buildings of 5 or more2%17%
Mobile homes2%3%
Built before 196052%32%
Built since 200011%22%
Middle year built19571975
Owner-occupied81%67%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.